Urotensin II was discovered as one of peptide hormones having a potent vasoconstrictive activity, and has been proved to have far higher vasoconstrictive activity than endothelin, which is the most potent vasoconstrictor among those which are currently known to have vasoconstrictive activity on mammal arteria. Further, it has been revealed that the receptor for urotensin II is GPR 14 protein, which is one of the orphan receptors (see, Nature, vol. 401, p. 282 (1999)).
On the other hand, somatostatin has been isolated and identified from sheep hypothalamus tissue as a factor for strongly suppressing secretion of growth hormone and is a peptide composed of 14 amino acids (SST-14). At present, somatostatin composed of 28 amino acids (SST-28) is also isolated and identified. This somatostatin is a brain-gut peptide widely distributed in not only hypothalamus, but also in brain, limbic system, spinal cord, vagus nerve, autonomic neuroganglion, gastrointestinal mucosa, pancreas Langerhans islets, etc., and suppresses secretion of pituitary-gastrointestinal hormones such as growth hormone, thyroid stimulating hormone, gastrin, insulin, glucagon, etc. Further, it suppresses secretion of gastric juice, pancreatic exocrine, and gastrointestinal movement and blood flow. As somatostatin receptors, up to the present, type 1 to type 5 (SSTR1, SSTR2, SSTR3, SSTR4, SSTR5) have been known and it is recognized that each of them shows different expression.    [1. Life Science, Vol. 57, No. 13, p. 1249 (1995)    2. Journal of Clinical Endocrinology and Metabolism, Vol. 80, No. 6, pp. 1789–1793    3. The New England Journal of Medicine, Jan. 25, 1996    4. Eur. J. Clin. Pharmacol., 1996, 51, 139–144    5. Exp. Opin. Ther. Patents (1998) 8 (7): 855–870]
As compounds having somatostatin receptor regulating activity, there are peptide compounds described in Life Science, 31, 1133–1140 (1982), Nature, 292, 55–58 (1981) and the like; and non peptide compounds described in JP 2000-191615 A, JP 2000-191648 A, JP 2000-226373 A, JP 11-209356 A and the like. As compounds having somatostatin receptor regulating activity and containing biphenyl in their structures, there are compounds described in JP 2000-226373 and the like.
Further, as biphenyl compounds, for example, JP 6-107649 A discloses biphenyl compounds having 5-HT (serotonin) receptor antagonistic activity and its Example 10 discloses 4′-[[(methoxyacetyl)methylamino]methyl]-N-[4-methoxy-3-(4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2′-methyl-[1,1′-biphenyl}-4-carboxamide hydrochloride.